Question

Xylem parenchyma can not be traced in
A. Monocots
B. Dicots
C. Pinus
D. Both A and C

Answer 1

Hint: Xylem and phloem are the vascular tissues seen in higher plants. It consists of four elements. Xylem parenchyma is one of the elements which helps in storing food and conduction of water and minerals.

Complete Answer:
Plant tissues are categorised into two categories- meristematic and permanent tissues. Permanent tissues are of two types- simple and complex. Complex permanent tissues include xylem and phloem. Complex tissues are made up of different types of cells. The word “xylem” is derived from the greek word “xylon” which means wood. It is a type of vascular tissue which helps in the conduction of water and minerals in the plants. The transport occurs from the roots to the stem and leaves.

Xylem is made up of four element-
1. Tracheids
2. Vessels
3. Xylem fibres
4. Xylem parenchyma: Xylem parenchyma is the living component of xylem which stores fats and starch. They are the parenchymatous cells which are associated with xylem.

There are two types of parenchyma cells in secondary xylem-
a. Axial parenchyma cells: The cells which are present in the axis.
b. Radial parenchyma cells: The cells which are arranged in the form of a ray and give a radiating appearance.

The main characteristics of xylem parenchyma are:
- Living cells.
- Thin cellulose cell walls.
- Prominent nucleus in the cells.
- Large vacuoles.
Axial and ray parenchyma cells which are present around vessels form outgrowth called “tyloses” and the cells which form these tyloses are called “contact cells”.

Functions of xylem parenchyma:
- Storage of food material.
- Ray parenchymatous cells cause radial conduction of water.
- Tyloses help in prevention of vascular tissues during infection.
- Maintain the xylem transport capacity.

Angiosperms are classified into monocots and dicots based on the number of cotyledons. The xylem parenchyma are absent in monocots. Dicots contain all the elements of xylem, Pinus is a gymnosperm which lacks the vessel element of xylem.

Hence the correct answer is option C.

Note: Xylem are the vascular tissues which help in the conduction of water and minerals. The monocots are the plants with seeds having single cotyledons. They do not contain xylem parenchyma which performs the main function of storage of food.